Field of the Invention
The present invention relates to wet wipes, more particularly to a natural preservative composition for such wipes.
Wet wipe products require preservatives in their aqueous phase to destroy or inhibit the growth of various microorganisms such as bacteria, yeasts and molds. The use of a chemical preservative agent dispersed or dissolved in the aqueous phase of a wet wipe lotion has become the conventional means for inhibiting microbiological activity. Recently, it has become commercially desirable to develop and market wet wipe products preserved with chemicals which are "natural", i.e., found in or derived from products of nature.
On such natural preservative is described and claimed in U.S. Pat. No. 4,732,797, granted Mar. 22, 1988 to Johnson et al. Johnson et al describe a wet wipe product comprising a liquid preservative composition having, as its sole active ingredients, citric acid and sorbic acid. Sorbic acid as a preservative for a wet wipe product has an esthetic and functional disadvantage: it is susceptible to oxidation and its oxidation products are yellow in color. Consequently, it tends to break down over time and color the wipe yellow unless some preventative measure is taken. Johnson et al. deal with this problem by protecting the sorbic acid with a high ratio, viz. 10 to 1, of citric acid, which protects the sorbic acid from oxidation (c.f., Johnson et al., Column 3, line 66 through Column 4, line 5). However, such a high proportion of citric acid means that in order to have an effective amount of sorbic acid present in the lotion, the amount of citric acid will be so high as to represent a threat to the physical integrity of the fibrous web unless the web is strongly bonded with an acid resistant binder. By following the teachings of the present invention, the need for sorbic acid as a component of the preservative composition can be reduced or eliminated.